An association may, by action of its board of directors and with the prior approval of the director, apply any part or all of any paid-in or contributed surplus or any surplus created by reduction of stock to the reduction or writing off of any deficit arising from losses or diminution in value of its assets, or may transfer to or designate as a part of its federal insurance account or any other reserve account irrevocably established for the sole purpose of absorbing losses, any part or all of any paid-in or contributed surplus or any surplus created by reduction of stock.